1. Field of the Invention
The present invention generally relates to a touch panel, and, in particular, to a touch panel and an input recognition device using the touch panel, which are for accurately recognizing a pen input.
2. Description of the Related Art
In general, a touch panel is installed on a display surface of a display device such as a Liquid Crystal Display (LCD), and generates a voltage or current signal when a user touches and presses the touch panel with a stylus pen or a finger as the user is looking at the display device. Input types of such a touchscreen include a resistance film and a capacitance.
The resistance film type touchscreen senses direct contact of two thin conduction layers on the screen by pressure applied onto the layers by a user's finger or stylus pen, and it does not matter whether the subject of sensing is a conductor or a nonconductor. By contrast, in the capacitance type touchscreen, the subject of sensing should be a conductor, and a predetermined contact area is required in order to change the sensible capacitance. Accordingly, there is no problem with sensing the finger. However, in the case of a conductor tip, its touch area is small, and thus the touch may not be sensed and cause errors to occur frequently. Even in the capacitance type, a stylus pen having a conductor tip, which is adjacent to the screen and generates an electric signal, can be used so that a user interface or an input by writing for a precise coordinate designation is possible. In the case of using an electronic pen or a stylus pen which has a built-in battery and generates an electric signal, electrode patterns, which are different from the existing capacitance type that can sense only the finger touch, are used in the touchscreen panel. In this case, a mutual capacitance type is used as the sense type.
Accordingly, the capacitance type is divided into a self-capacitance type and a mutual capacitance type. A self-capacitance type touch panel has a structure, as illustrated in FIG. 1. FIG. 1 illustrates an example of an electrode pattern 100 that is used to sense a finger in a general self-capacitance type touch panel. According to a detailed structure 110 of a diamond-patterned electrode pattern 100, a first pattern 120 is formed in a first direction, and a second pattern 130 is formed in a second direction, which is perpendicular to the first direction. The first pattern 120 and the second pattern 130 intersect. In the case where a portion indicated by a reference numeral 140 and a portion indicated by a reference numeral 150 in the electrode pattern are touched, the capacitance is proportional to the area, and, thus, a difference in signal size may occur even though a portion on the same pattern 130 is touched. Due to this difference in signal size, a coordinate detection error may occur at a touch point.
A mutual capacitance type touch panel has a structure as illustrated in FIG. 2. FIG. 2 illustrates an example of an electrode pattern 200 that is used to sense a stylus pen in a general mutual capacitance type touch panel. According to a detailed structure 210 of the lattice-patterned electrode pattern 200, as illustrated in FIG. 2, a first line 220 and second lines 230, 240, and 250 are formed in a first direction and in a second direction, respectively. In this type, as constituent elements, a transmission unit transmitting an electric field and a reception unit sensing the change of the electric field are dividedly provided to extract coordinates by sensing the change of the electric field that is caused by the contact of a conductor. If the intention is to sense the contact of a finger using this type, a method is used, which makes the electrode in the first direction function as the transmission unit and makes the electrode in the second direction function as the reception unit. If the intention is to sense the contact of a stylus pen, a method may be used, which makes the stylus pen itself serve to transmit the electric field instead of the electrode in the first direction. As described above, the touch panel of FIG. 2 has a structure that operates based on the mutual capacitance type.